Lodash - 搜索嵌套数组和返回对象

Question

I'm using Lodash to search a nested array and want return the object if it finds a match.

For each object, search for Bus 4. If found, return the object (in this case, school 'xyz').

var schools = [  
   {  
      "id":1,
      "school":"abc",
      "bus":[  
         {  
            "id":1,
            "name":"first bus"
         },
         {  
            "id":2,
            "name":"second bus"
         }
      ]
   },
   {  
      "id": 2,
      "school":"xyz",
      "bus":[  
         {  
            "id":3,
            "name":"third bus"
         },
         {  
            "id":4,
            "name":"fourth bus"
         }
      ]
   }
]

Here's what I have so far:

_.forEach(schools, function(school){console.log(_.where(school.bus, {'id':4}))})

Just spitting out the results. Kind of works.

Answer 1

First we should decide what function to use. Filter https://lodash.com/docs#filter fits our case because we want to return something that passes our evaluation.

The difficult part is crafting the evaluation. lodash does support searching through nested arrays, the syntax is actually quite intuitive once you learn it.

_.filter(schools,
  {
    bus: [{id: 4}]
  }
);

As opposed to if bus were not an array in which case it would be

_.filter(schools,
  {
    bus: {id: 4}
  }
);

caveat: filter will always return an array so if you want just the object be sure to append a [0] to it.